View Full Version : green wheel too soft?

08-17-2010, 09:33 PM
I bought a "green" silicon carbide wheel to touch up my carbide bits. I watched our know-it-all, who supposedly "ran a machine shop at NASA", grind down the shank on a wood cutting spade bit today. This is after I mentioned a while back that I bought the wheel for carbide, wood, brass ect... He asked me where I bought this piece of junk because it is too soft, the grit was falling off too fast. I thought a green wheel was supposed to be soft.?


08-17-2010, 09:45 PM
Yes green wheels are too soft for grinding spade drill shanks.. :)

08-17-2010, 10:33 PM
Green is soft, but it'll sharpen carbide.

A diamond wheel is better if you can afford it. But keep the shop genius away from it. :D

08-17-2010, 10:42 PM
Strictly speaking, silicon carbide is VERY had. However, the BOND in a green wheel is fairly weak, allowing the grains to break away as soon as the edges dull. This continally exposes fresh, sharp grains to the carbide. Norton and others publish a clear explanation of the wheel grading system, wherin they explain the importance of the type of bond for different applications, as well as the size of grit.

08-17-2010, 11:20 PM
a welding shop owner buddy bought a green wheel to touch up a 100 or so used carbide bits he bought. one of his welders watched the wheel dissappear all over his hands,shirt and pants trying to dress the head of a bolt. a 6" wheel went to 5" real quick. works great on carbide tools but steel will eat it like a marshmallow. if,like me, you only have one grinder,change wheels. dont use the green one for anything but carbide. i know,its a PITA.

08-18-2010, 12:47 AM
Having worked in the machine shop at a couple factories, it is anyone's guess as to what someone will bring in the shop to grind.

Most of the time one of us could help them- it was the ones that came in while you were out doing maintenance that would drive you crazy!

Some moron thought the soft wheel was for aluminum! After he got through with a new wheel, it was still roughly the new diameter but loaded so badly it may as well have been aluminum. It was impossible to do anything with it but throw it away!

It happened more than once- never caught that guy but would have liked to!

08-18-2010, 12:52 AM
Green wheels will get you there - like a horse and buggy. They are made to fall apart so new and sharp edges are exposed. Get a CBN or a Diamond wheel.

08-18-2010, 06:20 PM
Thank you gentlemen for clearing it up for me.


08-18-2010, 10:32 PM
CBN and Diamond are two different animals. CBN is mostly for high carbon high chrome. Diamond is mostly for carbide and anything harder than the humps of .... or use on someone who would grind steel with a green wheel.

I ground some mystery metal that was supposed to be harder than.... One pass and all the diamonds were gone from the wheel. :eek: (found out the stuff was 4340.... sheesh)

08-24-2010, 07:34 PM
A Diamond face wheel, plate mounted on a Baldor grinder type and some aluminum oxide dressing sticks(white sticks) it will get the job done.

08-24-2010, 08:48 PM
The B.I.L. used a green wheel I keep on one of the grinders once to sharpen lawnmower blades. :rolleyes: It went from a fresh 7" wheel to a rounded 5" wheel by the time he finished. Now I keep labels on all the machines and equipment. He laughs when he comes into the shop but it works. :D